I personally don't think RJJ could keep Matt Hughes/GSP/BJ Penn/Dan Henderson from getting the take down. As far as the age old discussion of how a world class boxer would fair against an equally talented MMA fighter in an MMA fight, well I personally believe that the boxers one dimensional fighting style simply dooms them most of the time and conversely I can't think of a single MMA fighter that I'd give any more than a punchers chance in a boxing match. I also feel that what works in traditional boxing(stance, defense, punching etc) do not directly correlate to MMA success. Great take down defense is something that takes a lot of work. If you dont' work on a great sprawl a good wrestler will put you on your back time and time again. You dont need to get that close(clinch) to use a good single and double leg take down, and in MMA they are quite often set up with strikes(albeit not usually effective). I usually like to pump a double jab then shoot in for a take down. I don't throw the punches b/c I think they are going to hurt my opponent, only to give me that split second I need to shoot. If you look at KO's that come on fighters shooting in, its almost always a knee not a punch that ends the fight. On a different note I think the typical statement of how sloppy and atrocious MMA punching is misguided. MMA is striking and boxing is punching. Although marginally similar they are not the same thing. I will agree that MMA striking is not nearly as technical as boxing but this is due to the gloves and variety of MMA. Its like comparing softball and baseball. Similar sports but with some very different aspects. Due to the variety of strikes available to a MMA fighter and the neccesity for takedown defense it is going to look vastly different. I'd quickly admit that boxers are the world experts on the best way to throw and setup a punch, but I think it also safe to say that the techniques used in the two sports for striking/punching have some large differences.